Method of making spiral cutters



A rilvzs, 1942. H, RUSKIN 2,281,250

METHOD OF MAKING vSPIRAL CUTTERS Filed Dec. 8f1938 2 Sheets-Sheet 1 56 1 IN ENTOR.

4 66 BY I H15 ATT RNEY.

H. RUSKIN METHOD 'OF MAKING SPIRAL GUTTERS April 28, 1942. 2,281,250

Filed Dec; a, 1958 -2 Sheets-Sheet 2 //////Z Qg/ INVENTOR.

E15 ATTCIDRN Patented Apr. 28, 1942 METHOD OF SPIRAL CUTTERS Henry Ruskin, Chicago, Ill, assignor of one-half to George E. Hale, Chicago, 111.

Application December 8, 1938, Serial No. 244,593

2 Claims.

I This invention pertains broadly to dry-shaving devices and more particularly to a method of making spiral cutters therefor.

A particular object of the invention is the provision of a spiral cutter in the form of a helix of steel ribbon, the outer peripheral surface portion of which is of greater width laterally across the ribbon than the inner peripheral surface thereof so as to form sharp cutting edges along the juncture of the outer peripheral surface of the ribbon with the remaining bodyportions thereof.

Another object is the provision in a dry-shave device of a movable cutting member which may be placed directly against the skin in effecting its cutting operation, due to certain peculiarities in the form and construction of the cutting elements.

Another object is the provision of a method of making a cutting helix in which a convolute steel ribbon is formed so as to have a somewhat triangular or trapezoidal cross section with the outerlateral surface of the ribbon sloping inwardly in a convergent mannerv so as to leave sharp edges along the juncture of the outer peripheral surface with the sloping body portions.

Another object is the provision of a stationary cutter or shear, and method of making the same, for cooperation with the spiral cutter and in which slots are formed with a certain pitch cocperable with the pitch of the spiral, and the slots are formed to provide combing teeth therebetween.

Yet another object is the provision of a cutter havingpitched teeth or slots of particular contour.

A furtherobject is the provision of a helical cutter, and method of making the same, in which there is a steel helix the convolutions of which are wider on their outer peripheral surface, transversely of the length thereof, than at their inner peripheral surface, the helix being.

of a unitary structure and having integral mounting means, or the helix being of a composite structure in which the helix is mounted on a mandrel.

Other novel aspects and objects of the invention reside in details of the construction, operation, form, and location of the parts of the device' of the illustrative embodiment, as well as in the various steps of the method of making said device, all of which is described hereinafter in conjunction with the annexed drawings, in which:

Fig. 1 is a perspective view of a cutting helix:

Fig. 2 is an enlarged fragmentary median section along line 2-2 of Fig. 1:

Fig. 2--A is a magnified sectional fragment of the helical cutting edges shown in Fig. 2;

Fig. 3 is a fragmentary front elevation of a modified cutter with pitched cutting slots and combing formations therebetween;

Fig. 4 is a transverse section along line [-6 of Fig. 3; v

Fig. 5 is a fragmentary front elevation of a stationary cutter having pitched shear slots and combing teeth for cooperation with the shear of Fig. 3;

Fig. 6 is a transverse section through the assembled cutter elements of Figs. 3 and 5 and drive means therefor;

Fig. 7 is a rear elevation of the movable shear of Fig. 4 as assembled in Fig. 6 showing the complex drive means;

Fig. 8 illustrates a modified spiral cutter and method of making the same. wherein the helix is mounted on a mandrelto provide a composite;

cutter with a single cutting edge:

Fig. 9 is amagnitled sectional fragment of the ribbon and method of mounting the same on its mandrel; while Fig. 10 is a modified form of composite helical cutter in' which the cutting helix is doubleedged;

Fig. 11 is an enlarged fragmentary perspective of a shaving device employing the helical cutter;

Fig. 12 is'an enlarged fragmentary vertical section through the shaving head and cutter, as seen along line l2--l2 of Fig. 11:

Fig. 13 is a fragmentary perspective of ad- Jacent turns of thecutting helix illustrating the complex motionthereof: while I I Fig. 14 is a magnified fragmentary section taken transversely through adjacent cutting turns of the helix to illustrate the cutting action thereof. V

This application is in part a continuation of my- United States Patent No. 2,161,981 oi June 13. 1939.

The invention of this application provides a new form of spiral cutter and a means for making the same which. due to inherent structural and functional characteristics to be brought out hereinafter. may be used in direct contact with the skin of the shaver withoutany guard whatever.

By employing the method disclosed herein, it

tance apart so that cutting variously for use in dry shaving devices and critical spacing between the turns controlled with a very high degree of accuracy. Moreover, the method makes possible the provision of extremely sharp cutting edges extending along the margins of the turns of the helix, the outer surfaces of the cutter nevertheless being flat so that they may safely bear against the skin of the shaver without the slightest danger of injury. Due to the fact that the spacing between the turns of the cutting helix is absolutely under control, such spacing may be held to a dimension which will preclude the possibility of skin entering between the turns of the helix where it could be cut or torn, the spacing nevertheless admitting hairs of a predetermined range of length and thickness between the turns.

In one of its forms, as illustrated in Fig. 1, the spiral cutter includes a helix lb of steel "ribbon or stock in which the convolutions are spaced from each other a predetermined amount as at i8 (Fig. 2 also), and in which one end I! is left open'while the opposite end is provided with an integral end plate l8 from which projects a stud shaft 19 having a slot 20, the stud shaft being mounted in a suitable bearing member to support the helix in cutting position, and a suitable drive means being connected to rotate the helix through the agency of the. slot 20. It should be observed that the axial extremities of the helix adjacent its open end H are enlarged to provide a collar 2|, the latter serving to support the helix in proper cutting positionin cooperation with its stationary shear.

An important peculiarity of the cutting helix is the cross sectional shape of the ribbon forming its convolutions, this cross sectional shape being particularly illustrated in Fig. 2 wherein it will be observed that the outer peripheral surface 25 of the ribbon is wider in a direction laterally across the same than the inner peripheral surface 25 thereof whereby the intervening side helices may be made wall or body portions 21 tend to converge in the surface 26 so that the junctures 28 between the outer peripheral surface and the remaining body portions, for example, the sloping sides 21, provides a sharp cutting edge along the opposite outer peripheral edges of the ribbon or convolutions of the helix. It is to be understood that the term ribbon" as used herein is intended to apply both to a relatively flat and narrow length of stock such as shown, for example, in Fig. 8, and to the relatively thick stock shown in Fig. 2, except as may be otherwise specifically provided hereinafter.

As a result of the foregoing cross sectional shape of the ribbon or filamentary stock from which the spiral or helix is wound or formed, the cutting edges 28 are self-sharpening in those arrangements wherein the cutting helix is employed with a stationary shear against which the outer peripheral portions of the helix bear during rotation.

Another important feature of the invention is the method provided for making a cutting helix such as shown in Fig. 1. In this method, a rod of steel, preferably cylindrical in shape, is drilled from one end, which corresponds to the open end 57 of the helix i5, to a depth substantially equivalent to the desired depth of the helix, the bore terminating at the end plate or wall is, and at a suitable stage in the procedure the stock is turned down to form a stud shaft is which is integral with the plate l8. When the bore has been completed. the resulting tubular stock is threaded internally so as to provide the threads 30 (Fig. 2), the crest or ridge portions ll of which maybe of any degree of sharpness ranging from a relatively flat land such as is shown in my aforementioned copending application, to a sharp ridge, the ridge portions ii of the present threading being slightly rounded and constituting the inner peripheral surface of the convolutions of the spiral or helix. The intervening recessed portions or valleys 32 (Fig. 2-A also) between the ridge portions Ii of the threads are termed herein for purposes convenience of the troughs.

A tap suitable for use in threading the sleeve, and one which results in a thread having a contour and pitch especially suitable in the production of a cutting helix for use in a dry shaver. is one which is threaded with a Whltworth standard thread %"-l6.

After the sleeve form or bore has been tapped as aforesaid, the same is placed in a lathe or grinding machine, and the outer peripheral portions thereof are ground down so as to leave the collar 2| at one end thereof, the grinding or turning being continued to a depth sumcient to cut through the trough portions 32 between each internal thread and until the trough portions have been cut to a certain depth to provide the desired spacing I8 between the turns of the helix.

In the embodiment of Fig. 2, which illustrates the contour of thread resulting from the employment of a tap of the type mentioned, it will be observed that the slope of the side portions 21 of each thread decreases and tends to level off as these sides approach their junctures 28 with the outer peripheral surface 25 of the helix so that acutely sharp cutting edges 33 will result (Fig. 2-A).

The slope of the sides 21 may be made straight if it is desired to have the cutting edge wear down uniformly, although in this arrangement there is some sacrifice of initial sharpness, the cutting edges 38 shown in Fig. 2-A being extremely sharp in the first instance, so sharp, in fact, that the spiral has been used without any cooperating stationary shear or guard but placed directly against the skin, and the spiral cutting edges of themselves positively cut hair.

In the modified form of spiral cutter shown in Fig. 8, a steel ribbon 40 of relatively thinner stock than that which results in the ribbon convolutions of the spiral of Fig. 2, is ground along one of its inner edge portions to provide a cutting edge 4! which, as will be observed in the enlarged view of Fig. 9, slopes outwardly from the inner peripheral surface 62 of the ribbon to the outer peripheral surface 13 thereof, the pitch of the sloping side portion Ml which results from the grinding, however, being uniform, as distinguished from the curvilinear pitch shown in Fig. 2-25.

After grinding as aforesaid, the steel ribbon at is wound spirally upon a sleeve or tubular mandrel 65 on the outer peripheral portions of which have been provided threads 48 of square configuration and having particularly fiat lands or tops d? which engage the inner peripheral surfaces 32 of the helical ribbon, the helix being wound or tightly fitted over the mandrel and the threads 66 thereon, and the ribbon being secured to the mandrel by means such as pins 48 which are driven through the ribbon into the threads as at suitable intervals. A collar 49 may be sweated onto the endmost portions of the helix at the open end ll thereof, while the opposite end of the mandrel 48 may be provided with an end plate and stud shaft, such as shown in Fig. i. In a modified arrangement of the ribbon spiral shown in Fig. 9, the mandrel a has its spiral threading or ridges 4811 provided with an opensided groove 80 along the top land at one side thereof so as to leave a spiral ridge ill, the inner peripheral surface portions 42 of the spiral ribbon being wound into the groove or track 50 with the unsharpened edge portion 52 thereof abutting the ridge SI. and pin means it being driven through the ribbon into the main ridge portion 6a. This latter arrangement provides a mounting for the cutting spiral which is exceedingly rigid and strong.

In still another modified arrangement of the sharpened steel ribbon, the ribbon 55 (Fig. is sharpened along both edges from its inner periphery to provide ccnvergently sloping sides 88 extending from the outer peripheral surface thereof so that opposite cutting edges 51 will result, the sloping sides converging in a ridge 58 which constitutes an inner peripheral portionoi the spiral analogous to the inner peripheral ridge portions ll of the arrangement of Fig. 2. In order to mount the cutting ribbon of Fig. 10, the mandrel b has its ridge portio'ns 46b spaced somewhat farther apart with the top land portions thereof cut to provide a V-shaped seating groove 58 into which the convergent sides 56 of the ribbon ilt firmly, the ribbon preferably being threaded onto the ridges 48b and gripping the latter tightly enough so that no other attaching means is necessary, an end collar analogous to the collar ll oi the arrangement of Fig. 8 likewise being applied to this latter form of helix and serving to prevent the ribbon from working oil of the mandrel.

In Fig. 3 there is shown a movable cutter in the form of a sleeve member 00 having a plurality oi oblate openings 6| aligned thereacross in a direction transverse to the long axis oi the sleeve. these openings constituting shear slots, and being pitched or slanted relative to the aforesaid axis of the sleeve at a predetermined angle for reasons which will appear hereinafter. The curved marginal portions 62 of the oblate shearing slots are sharp as. a result of the fact that the intervening body portions 63 therebetween are, in a manner of speaking. undercut in the sense that the inner peripheral portions of the helix of Fig. 2 may be said to be undercut.

In forming the cutter of Fig. 3, a piece of steel stock of preferably tubular form is provided with an eccentric bore 64, which bore is subsequently tapped and threaded with a thread similar to that used in Fig. 2, if desired. the pitch and shape of the thread being determined largely by the various resultant cutting characteristics which may be required in one or another instance. When the bore has been tapped, the stock is placed in a lathe or grinding machine arranged toturn down the outerperipheral portions of the drilled and tapped stock concentrically with the cylindrical stock and eccentrically to the bore, with the result that the wall of the sleeve in the region indicated at 6 is turned down until the trough portions of the thread have been cut through in a manner -described in conjunction with the process of Fig. 2, the oblate form 01' the slots I in the cutter of Fig. 3, however, resulting from the eccentricity oi the bore in grinding- This oblate tom of the slots is of importance due to the fact that hairs, particularly stubble,-may readily project. into the wider portions thereof,

as the shaving device is moved over the face. to be worked toward the narrower portions of the slot, as the implement progresses over the surface being shaved.

A stationary guard or shear particularly suited for cooperation with the cutter of Fig. 31s illustrated in Fig. 5 and includes a substantially cylindrical tubular guard Ill which is formed from a piece of steel stock in which there has been drilled an eccentric bore II, and the outer periphery of which has been threaded to provide an external thread 12. After, the guard has been threaded, it is placed in a lathe or grinding machine andturned down eccentrically so that all of the threading. save that in the region indicated at 13, is cut away. that portion of the threading in the region 18 likewise being slightly ground down so as to provide a flat outer peripheral surface suitable for contact with the skin;

Thereafter, the bore II is ground away eccentrically so as to cut through the trough portions 01 the threading between the threads 12 thereof to, provide somewhat oblate openings 14 which, however, are'pitched oppositely to the cooperating shear slots BI 01 the movable cutter ot-Fig. 3 as a result oi employing a reverse thread in the stationary member of F18. 5. It will be observed also in Fig. -5 that there is a slight twist in the appearance ofthe shear slots in the stationary I guard sleeve Hi; this results from the pitch of the thread and the eccentricity oi the grinding.

In operative relationship, the movable cutting member oi Fig. 3 is dimensioned to have a close sliding movement within the stationary member or guard I0. the latter, in assembled relation. being secured to the head of a handle member I! (Fig.6) by means such as the screws 18, and there being a rotating crank shaft 'I'l. driven by the usual motor means in the handle casing and which extends through a suitable opening 18 in the base of the sleeve III. A crank pin it is mounted eccentrically on the, end of the shaft II and projects into an elongated slot 86 (Figsai. 6 and 'l) in a rear peripheral surface of the inner or moving cutting member 80.

As crank shalt-i1 rotates, the crank pin 19 in the end thereof will rock the inner cutting member ill so that the slot 68 thereof will be moved in opposite directions rapidly into and out o! thedotted line positions of the slot indicated in Fig.

7, and substantially at the same time the crank pin 19, riding in one, left-hand. end oi the slot it to the other, right-hand, end thereof, will reelprocate the cutter 00. the motion oi the latter thus being complex, with the result that the shearing slot Si in the member 60 will be moved at approximately the same time in a' clipping movement across the slots M in the guard, and

in a shearing motion as a result oi the rocking movement thereof. Both the opposite pitch and the twist of the slots 14 in the stationary member cooperate with the slots II to give a particularly elllcient shearing action, the oblate form of the shearing slots, moreover. alone, and in combination with the combing formations aflorded by the ground-down external threads 12 in the guard being peculiarly eilective to guide the beard into the slots.

One arrangement for employing the helical cutter 01' Fig. l in a shaving device, is illustrated in Figs. 11 and 12 wherein the-cutter It is mounted for rotation between a pair of separable casing members I0 and BI secured together by means such as the bolt 82, so that the cutter is disposed at an angle to the handle portion 03 of the remainder of the casing. as illustrated in Fig. 11, whereby the cutter may be conveniently manipulated relative to the shaving surface. A driven gear .84 is drivingly engaged with the slotted end portion 20, as seen in Fig. 12, wherein a lug 85 on the gear '4 is disposed in the slot 20 on the stud shaft is of a cutter made in accordance with the arrangement of Fig. l. The opposite or free end of the helical cutter is exposed at the opposite end 88 of the head, and the collar portion 2| (not seen) rides on the inner peripheral portions of the casing members 80 and ll. The gear II is driven by another gear 81 having connection with an electric motor in the handle portion 83 of the casing.

The outer edge portions as and 89 of the separable members of the head are beveled so as to have horizontal marginal edges 90 and Si disposed closely against or at the periphery of the cutting helix, these marginal edges defining a horizontal open slot through which a predetermined portion of the peripheral surface of the helix is exposed for direct contact with the face of the shaver. The inner surface portions of the separable casing head members are relieved by channeling 82 to reduce the friction of the helix in rotation.

A cover plate 95 is fitted around the shaving head and secured in place by .bolts 82 with an elongated open slot 8'! registered with the slot formed by the members 80 and 8| so that the predetermined peripheral surface portion of the cutting helix is exposed for direct contact with the face of the shaver.

In the cutting operation of the helix as employed in the arrangement of Fig. 11, it is pointed out that the turns of the helix have two degrees of movement in their cutting action, this being brought out in Fig. 13, wherein the tracer arrows I indicate the rotative motion of the turns, while the tracer arrows l0! indicate the translating or axially shifting cyclic motion of the turns.

The importance of this, in addition to simplifying the manufacture of the shaving implement by omitting the guard, resides in the fact that an ordinary cutter or blade moving only transversely of a bristle, tends to bend the latter over prior to and during the cutting operation with the result that the bristle is not shorn in a perfectlytransverse section, but is cut obliquely so that the cut portion of the bristle, instead of being substantially cylindrical in appearance, is elliptical. Thus, while a blade which moves only transversely may have begun its cutting action at a point very close to the base of the bristle. this action may end at a point appreciably farther away from the base, so that the hair is not cut as short as it should be. Such incomplete or oblique cutting is substantially eliminated by the present invention.

The rotative movement of the cutting edges of the helix simultaneously with their translatory movement, eiIects a slicing action, as well as a direct cut, so that the bristles are shorn evenly across and very close to the skin, as is brought out in the diagrammatic illustration of Fig. 14.

Unless otherwise expressly provided, the recitation in the appended claims, in a certain order, of the various steps in the fabrication of cutters or members having slots such as hereinbefore described, is not to be construed as requiring such steps to be eflected in the order named, except where the operation by its very nature requires that it be efiected in a particular order with relation to the other steps of the method.

The objects and advantages of the invention both with respect to the method and the product thereof, may be realized by other forms of construction and changes in the procedure of the method without departing from the broad spirit of the invention, and it is a condition of this disclosure that all equivalent arrangements and methods are to be included within the call of the appended claims.

Having thus described my invention, what I claim as new and desire to protect by Letters .Patent is:

1. The method of making cutters with spirally pitched shear slots, which comprises drilling an eccentric bore in apiece of cylindrically formed stock, threading said bore with a thread of the desired pitch of said slots, and grinding the exterior surface portions radially of said bore and eccentrically relative to said bore until the trough portions between said threading are cut through to provide slots pitched conformably with the pitch of said threading.

2. The method of making cutters which comprises the provision of a bore in a piece of stock, cutting a spiral groove in said bore, and grinding said piece of stock exteriorly and eccentrically relative to said bore whereby to grind away a portion of said stock in the region of the latter having substantially the closest radial distance to the center of said bore, said grinding being continued until the base portions of said stock, in said last-mentioned region, between the ridge portions of said spiral groove, are'cut through.

HENRY RUSKIN. 

